The economical and easy transportation of a plurality of articles which must be maintained substantially horizontal with respect to the ground presents unique problems. In the greenhouse industry in particular, the transportation of a plurality of trays of flowers or other bedding plants has been a time-consuming and back-breaking job. The trays must be maintained in a generally horizontal relationship to the ground in order to prevent the contents therein from being spilled out. The manual carrying of such trays to maintain them in a generally horizontal relationship to the ground is extremely impractical as well as very tiring if a number of such trays must be transported.